Stability Simulation and Angle Optimization for Open-Pit Rock Slopes Under Multi-Condition Coupling

Abstract

To achieve the optimal balance between structural safety and stripping economy for the rock slopes of a specific open-pit iron mine, a rigorous mathematical modeling and computational framework was established. In contrast to traditional simplified pseudo-static evaluations, authentic monitored seismic and blasting waveforms were integrated within an explicit dynamic strength reduction model to ensure that transient stress wave propagation and progressive failure paths of rock slopes were accurately captured. Furthermore, a constrained multi-objective optimization model was established so that the nonlinear trade-off between dynamic safety margins and stripping volumes could be quantitatively resolved. Based on the application to the studied open-pit slopes, it was revealed that severe deep plastic yielding and topological shear band coalescence were caused by transient dynamic stress waves when the slope angle was steepened to 45°. Consequently, the factor of safety (FS) was abruptly reduced to an unsafe range of 1.01 to 1.20. Through the effective exclusion of this high-risk 45° configuration, a global optimal mining slope angle of 42° was rigorously established. At this optimal angle, a robust factor of safety ranging from 1.45 to 1.98 was consistently maintained across all extreme multi-field coupled conditions. Ultimately, from an engineering perspective, dynamic shear failure paths were successfully interrupted, and the need for expensive structural reinforcement was eliminated. Economically, waste rock stripping volumes were significantly minimized, whereby the overall stripping ratio was optimized, and life-cycle excavation efficiency was maximized.